Armour is an abstract, it's not specifically something being broken, if your hazmat suit has a hole in it, it's not going guy stop any air born disease until util patch it, but until it gets that hole, it's not going to strangely decay just because you're standing in noxious fumes.
Slipping on ice is rng, but it's not dependable and only affects people moving through it. It also doesn't care if you have no armour, it's one ofa few cc affects that works despite your armour values. What you can't do is force people to be affected by it, it's not the same as having an aoe that knocks down.
I don't really care what you think about the difficulty of the combat, because all your suggestion does is make it even dumber. It's not hard to understand, with your system you just dump on the enemy and luck factors more into things than before. That's not a good thing.
The enemy has to win once to get a game over, you have to go through hundreds of fights. If fights devolve into, who gets lucky with rng, then you're going to lose more than not, and any time you win is going to be about luck rather than strategy.
Xcom is a completely different game built around improving odds, which is it's own problem with games like darkest dungeon where it's more about gaming the game than just playing it.
gambling on some rng cc affect is not a deep strategic decision. It's just a sign of gambling addiction.